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Lopez-Valladares, Gloria
Publications (10 of 12) Show all publications
Lopez-Valladares, G., Danielsson-Tham, M.-L., Goering, R. V. & Tham, W. (2017). Lineage II (Serovar 1/2a and 1/2c) Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis Types Divided into PFGE Groups Using the Band Patterns Below 145.5 kb. Foodborne pathogens and disease, 14(1), 8-16
Open this publication in new window or tab >>Lineage II (Serovar 1/2a and 1/2c) Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis Types Divided into PFGE Groups Using the Band Patterns Below 145.5 kb
2017 (English)In: Foodborne pathogens and disease, ISSN 1535-3141, E-ISSN 1556-7125, Vol. 14, no 1, p. 8-16Article in journal (Refereed) Published
Abstract [en]

Among 504 clinical lineage II isolates of Listeria monocytogenes isolated during 1958-2010 in Sweden, 119 pulsed-field gel electrophoresis (PFGE) types (AscI) have been identified based on the number and distribution of all banding patterns in each DNA profile. In this study, these types were further divided into PFGE groups based on the configuration of small bands with sizes <145.5 kb. The 504 isolates included 483 serovar 1/2a isolates distributed into 114 PFGE types and 21 serovar 1/2c isolates distributed into 9 PFGE types; these were further divided into 21 PFGE groups. PFGE group, that is, configuration of small bands below 145.5 kb, and serovars were correlated. L. monocytogenes isolates belonging to PFGE groups A, B, C, E, F, H, K, L, M, S, V, W, Y, and Ö-6 to Ö-12 shared serovar 1/2a, with one exception. PFGE group E also included two PFGE types sharing serovar 1/2c and four PFGE types belonging to either serovar 1/2a or 1/2c. Isolates belonging to PFGE group N shared serovar 1/2c. In contrast to lineage I isolates, small fragments <33.3 kb were visible in all L. monocytogenes isolates belonging to lineage II. In the results from both the present and previous studies, the genomic region of small bands was genetically more conservative than in large bands. The distribution of these small bands established the relatedness of strains and defined a genetic marker for both lineages I and II, while also establishing their serogroup. The division of L. monocytogenes PFGE types into PFGE groups is advantageous as the profile of every new isolate can be identified easily and quickly through first studying the PFGE group affiliation of the isolate based on the smaller band patterns <145.5 kb, and then identifying the PFGE type based on the band patterns >145.5 kb.

Place, publisher, year, edition, pages
New Rochelle, USA: Mary Ann Liebert, 2017
Keywords
PFGE type, PFGE group, Listeria monocytogenes, serovar, lineage II
National Category
Genetics Food Science
Identifiers
urn:nbn:se:oru:diva-53597 (URN)10.1089/fpd.2016.2173 (DOI)000391818800002 ()27860487 (PubMedID)2-s2.0-85009260194 (Scopus ID)
Note

Funding Agency:

Stiftelsen Grythytte Akademi Stipendiefond

Available from: 2016-11-21 Created: 2016-11-21 Last updated: 2018-07-28Bibliographically approved
Lopez-Valladares, G., Danielsson-Tham, M.-L. & Tham, W. (2016). Listeria monocytogenes: a threat to the health of restaurant guests. In: Tobias Nygren, Agneta Yngve och Åsa Öström (Ed.), 1st Granqvist Culinary Arts and Meal Science Symposium: Programme and Abstracts. Paper presented at 1st Granqvist Culinary Arts and Meal Science Symposium, Grythyttan, 18 March, 2016 (pp. 35-35). Örebro: Örebro University, 1
Open this publication in new window or tab >>Listeria monocytogenes: a threat to the health of restaurant guests
2016 (English)In: 1st Granqvist Culinary Arts and Meal Science Symposium: Programme and Abstracts / [ed] Tobias Nygren, Agneta Yngve och Åsa Öström, Örebro: Örebro University , 2016, Vol. 1, p. 35-35Conference paper, Poster (with or without abstract) (Refereed)
Place, publisher, year, edition, pages
Örebro: Örebro University, 2016
National Category
Medical and Health Sciences Nutrition and Dietetics
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-49450 (URN)
Conference
1st Granqvist Culinary Arts and Meal Science Symposium, Grythyttan, 18 March, 2016
Available from: 2016-03-22 Created: 2016-03-22 Last updated: 2017-10-17Bibliographically approved
Lopez-Valladares, G., Danielsson-Tham, M.-L., Goering, R. V. & Tham, W. (2015). Division of Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis (PFGE) Types Belonging to Lineage I (Serovar 4b, 1/2b, and 3b) into PFGE Groups. Foodborne pathogens and disease, 12(5), 447-453
Open this publication in new window or tab >>Division of Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis (PFGE) Types Belonging to Lineage I (Serovar 4b, 1/2b, and 3b) into PFGE Groups
2015 (English)In: Foodborne pathogens and disease, ISSN 1535-3141, E-ISSN 1556-7125, Vol. 12, no 5, p. 447-453Article in journal (Refereed) Published
Abstract [en]

The 63 pulsed-field gel electrophoresis (PFGE) types identified among 427 clinical isolates of Listeria monocytogenes that were characterized in a previous study by serotyping and PFGE (AscI) could be further divided into 17 PFGE groups. While the 63 PFGE types, all part of lineage I, were established based on the number and distribution of all bands in each DNA profile, the 17 PFGE groups were based on the configuration of small bands with sizes L. monocytogenes serovar 4b isolates (n=334) were divided into 8 PFGE groups; the 32 PFGE types of serovar 1/2b isolates (n=90) and the serovar 3b isolates (n=3, 1 PFGE type) were divided into 9 PFGE groups. An association was observed between PFGE groups and serovars. L. monocytogenes isolates belonging to PFGE groups I, J, Q, R, X, Z, o-4, and o-5 all shared serovar 4b, whereas isolates from PFGE groups D, G, O, P, T, U, o-1, o-2, and o-3 shared serovar 1/2b. Small fragments L. monocytogenes isolates. From the results of the present study, a procedure for accelerating the identification of PFGE types when analyzing new PFGE profiles can be suggested. Therefore, we propose a stepwise procedure to PFGE profiling by first identifying the PFGE group using the smaller band patterns <145.5 kb, and then determining PFGE types based on the band patterns >145.5 kb.

Place, publisher, year, edition, pages
Mary Ann Liebert, 2015
National Category
Other Social Sciences not elsewhere specified
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-44674 (URN)10.1089/fpd.2014.1880 (DOI)000353777800010 ()25803595 (PubMedID)
Note

Funding Agency:

Stiftelsen Grythytte Akademi Stipendiefond

Available from: 2015-05-22 Created: 2015-05-22 Last updated: 2018-06-30Bibliographically approved
Lopez-Valladares, G., Tham, W., Parihar, V. S., Helmersson, S., Andersson, B., Ivarsson, S., . . . Danielsson-Tham, M.-L. (2014). Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010). Epidemiology and Infection, 142, 2251-2260
Open this publication in new window or tab >>Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010)
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2014 (English)In: Epidemiology and Infection, ISSN 0950-2688, E-ISSN 1469-4409, Vol. 142, p. 2251-2260Article in journal (Refereed) Published
Abstract [en]

Isolates of Listeria monocytogenes (n=932) isolated in Sweden during 1958–2010 from human patients with invasive listeriosis were characterized by serotyping and pulsed-field gel electrophoresis (PFGE) (AscI). Of the 932 isolates, 183 different PFGE types were identified, of which 83 were each represented by only one isolate. In all, 483 serovar 1/2a isolates were distributed over 114 PFGE types; 90 serovar 1/2b isolates gave 32 PFGE types; 21 serovar 1/2c isolates gave nine PFGE types; three serovar 3b isolates gave one PFGE type; and, 335 serovar 4b isolates gave 31 PFGE types. During the 1980s in Sweden, several serovar 4b cases were associated with the consumption of European raw soft cheese. However, as cheese-production hygiene has improved, the number of 4b cases has decreased. Since 1996, serovar 1/2a has been the dominant L. monocytogenes serovar in human listeriosis in Sweden. Therefore, based on current serovars and PFGE types, an association between human cases of listeriosis and the consumption of vacuum-packed gravad and cold-smoked salmon is suggested.

Keywords
Cheese, Listeria monocytogenes, PFGE, serotyping, salmon
National Category
Occupational Health and Environmental Health
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-40067 (URN)10.1017/S0950268813003385 (DOI)000344921000003 ()24480252 (PubMedID)2-s2.0-84909991349 (Scopus ID)
Note

Funding Agency:

Research Foundation of Ivar and Elsa Sandberg 

Available from: 2014-12-30 Created: 2014-12-30 Last updated: 2018-01-11Bibliographically approved
Lopez-Valladares, G., Danielsson-Tham, M.-L. & Than, W. (2013). Listeriosis in South American camelids: a review. Journal of Camel Practice and Research, 20, 129-132
Open this publication in new window or tab >>Listeriosis in South American camelids: a review
2013 (English)In: Journal of Camel Practice and Research, ISSN 0971-6777, E-ISSN 2277-8934, Vol. 20, p. 129-132Article in journal (Refereed) Published
Abstract [en]

The main aim of the present study was to review the general aspects of Listeria and the clinical manifestation of the disease listeriosis in humans and domestic ruminants, with emphasis on clinical signs in South American camelids. Camelids are susceptible to infection by Listeria; however, it appears that the prevalence of listeriosis in camelids is low, given that few cases have been reported. The species Listeria monocytogenes is associated with all reported cases. To our knowledge, there are no reported cases of listeriosis in vicunas (Vicugna vicugna) and guanacos (Lama guanicoe).

The clinical manifestations of listeriosis in llamas and alpacas are similar to in domestic ruminants and humans, namely meningoencephalitis, encephalitis, septicaemia, abortion, otitis media/interna and polyarthritis. Listerial mastitis and gastroenteritis has not yet been described in camelids. Despite reported cases, there is no specific mention of listeriosis associated with shedding of bacteria in faeces or milk. The occurrence of listeriosis in camelids needs to be confirmed and clinical signs defined.

Place, publisher, year, edition, pages
Camel Publ House, 2013
Keywords
Listeria, listeriosis, South American camelids
National Category
Other Social Sciences not elsewhere specified
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-40069 (URN)000325836200027 ()2-s2.0-84901767944 (Scopus ID)
Available from: 2014-12-30 Created: 2014-12-30 Last updated: 2017-12-05Bibliographically approved
Tham, W., Lopez-Valladares, G., Helmersson, S., Wennström, S., Österlund, A. & Danielsson-Tham, M.-L. (2013). Occurrence of Genetic Variants of Listeria monocytogenes Strains. Foodborne pathogens and disease, 10(9), 825-826
Open this publication in new window or tab >>Occurrence of Genetic Variants of Listeria monocytogenes Strains
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2013 (English)In: Foodborne pathogens and disease, ISSN 1535-3141, E-ISSN 1556-7125, Vol. 10, no 9, p. 825-826Article in journal (Refereed) Published
Abstract [en]

Isolates of Listeria monocytogenes saved from outbreaks of listeriosis, cases of sporadic listeriosis, and similar events do not always belong to a solitary genetic variant. Variants of the same strain may have evolved from a unique clone, and plasmid loss or gain and phage-mediated genetic changes are suggested as the main mechanism. Some of these reports are summarized in this short communication.

Place, publisher, year, edition, pages
Mary Ann Liebert, 2013
National Category
Food Science
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-34287 (URN)10.1089/fpd.2012.1456 (DOI)000330456900012 ()
Available from: 2014-03-13 Created: 2014-03-13 Last updated: 2017-12-05Bibliographically approved
Thisted Lambertz, S., Ivarsson, S., Lopez-Valladares, G., Sidstedt, M. & Lindqvist, R. (2013). Subtyping of Listeria monocytogenes isolates recovered from retail ready-to-eat foods, processing plants and listeriosis patients in Sweden 2010. International Journal of Food Microbiology, 166, 186-192
Open this publication in new window or tab >>Subtyping of Listeria monocytogenes isolates recovered from retail ready-to-eat foods, processing plants and listeriosis patients in Sweden 2010
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2013 (English)In: International Journal of Food Microbiology, ISSN 0168-1605, E-ISSN 1879-3460, Vol. 166, p. 186-192Article in journal (Refereed) Published
Abstract [en]

Identification and prioritisation of food safety interventions requires an understanding of the relationship be- tween food, pathogens and cases. Such understanding can be gained through different approaches, e.g. microbial subtyping to attribute cases of foodborne disease to food vehicles or other sources of illness. In this study, Listeria monocytogenes isolates (n = 166) from (i) three categories of ready-to-eat (RTE) foods, (ii) food processing plant environments, and (iii) human listeriosis cases, all sampled during 2010 in Sweden, were subtyped. In addition, 121 isolates from human listeriosis cases, collected 2005–2009, were subtyped. Subtyping consisted of both serotyping (conventional method and PCR) and genotyping using pulsed-field gel electrophoresis (PFGE). Serotype 1/2a dominated in all three groups of isolates (range 73–96%). Eighteen percent of the human isolates (2010) belonged to serotype 4b, but only 1.4% of the food isolates. The food isolates differentiated into 19 pulsotypes (ID = 0.843), the human isolates collected 2010 into 31 pulsotypes (ID = 0.950) and the processing plant isolates into 22 pulsotypes (ID = 0.991). Six of the pulsotypes were shared between the food and human isolates. These pulsotypes comprised 42% of the human isolates and 59% of the food isolates. For some processing plants, there was suggested persistence of one or more specific L. monocytogenes strains, as indicated by repetitive isolation of the same pulsotype from food. This study indicated the presence of L. monocytogenes in the processing plant environment as a likely source of contamination of gravad and cold-smoked fish, and this food category as an important source of human exposure to the pathogen

Place, publisher, year, edition, pages
Amsterdam, Netherlands: Elsevier, 2013
National Category
Social Sciences
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-40068 (URN)000324349300027 ()
Available from: 2014-12-30 Created: 2014-12-30 Last updated: 2018-05-22Bibliographically approved
Tham, W., Lopez-Valladares, G., Wennström, S., Österlund, A. & Danielsson-Tham, M.-L. (2010). Appearance of two closely related variants of Listeria monocytogenes inblood from the same patient with invasive listeriosis. In: Wilhelm Tham & Marie-Louiuse Danielsson-Tham (Ed.), Second Sympsoium on Food Associated Pathogens. Paper presented at Second Sympsoium on Food Associated Pathogens (pp. Abstr 29). Grythyttan: Restaurang- och hotellhögskolan – Grythytte Akademi
Open this publication in new window or tab >>Appearance of two closely related variants of Listeria monocytogenes inblood from the same patient with invasive listeriosis
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2010 (English)In: Second Sympsoium on Food Associated Pathogens / [ed] Wilhelm Tham & Marie-Louiuse Danielsson-Tham, Grythyttan: Restaurang- och hotellhögskolan – Grythytte Akademi , 2010, p. Abstr 29-Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Grythyttan: Restaurang- och hotellhögskolan – Grythytte Akademi, 2010
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-14075 (URN)978-91-7668-749-9 (ISBN)
Conference
Second Sympsoium on Food Associated Pathogens
Available from: 2011-01-22 Created: 2011-01-19 Last updated: 2017-10-17Bibliographically approved
Peiris, I. P., Lopez-Valladares, G., Parihar, V. S., Helmersson, S., Barbuddhe, S., Tham, W. & Danielsson-Tham, M.-L. (2009). Gravad (Gravlax) and cold-smoked salmon, still a potential source of listeriosis. Journal of Foodservice, 20(1), 15-20
Open this publication in new window or tab >>Gravad (Gravlax) and cold-smoked salmon, still a potential source of listeriosis
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2009 (English)In: Journal of Foodservice, ISSN 1748-0140, Vol. 20, no 1, p. 15-20Article in journal (Refereed) Published
Abstract [en]

Gravad (Gravlax) and cold-smoked salmon are associated with human listeriosis in Sweden. The present investigation of Listeria monocytogenes in salmon was a follow-up of a similar study in the middle of the 1990s. Since our first study, there has been an increasing focus on food hygiene in general and specially on self-inspection and Hazard Analysis and Critical Control Points from the authorities and food producers. L. monocytogenes was isolated from 11 (three manufacturers) of the 56 products analyzed. The highest level of L. monocytogenes was 1500 cfu/g from a cold-smoked salmon product; however, the level was low (<100 cfu/g) in most products. Serovar 1/2a was predominant, followed by 4b. restriction enzyme analysis/ pulsed-field gel electrophoresis typing of the 56 salmon isolates identified five types of L. monocytogenes. One type was identical to a human type, whereas two other were closely related. These findings suggest that gravad and coldsmoked salmon are still possible sources of listeriosis in Sweden.

Place, publisher, year, edition, pages
Oxford: Blackwell Publishing, 2009
National Category
Medical and Health Sciences
Research subject
Culinary Arts and Meal Science; Biomedicine
Identifiers
urn:nbn:se:oru:diva-2999 (URN)10.1111/j.1748-0159.2008.00118.x (DOI)
Available from: 2008-09-05 Created: 2008-09-05 Last updated: 2017-10-18Bibliographically approved
Tham, W., Lopez-Valladares, G. & Danielsson-Tham, M.-L. (2009). Humanisolat av Listeria monocytogenes under ett halvt sekel i Sverige. In: P. Jonsson, B. Larsson (Ed.), Veterinärkongressen 2009. Paper presented at Veterinärkongressen 2009 (pp. 91-92).
Open this publication in new window or tab >>Humanisolat av Listeria monocytogenes under ett halvt sekel i Sverige
2009 (Swedish)In: Veterinärkongressen 2009 / [ed] P. Jonsson, B. Larsson, 2009, p. 91-92Conference paper, Oral presentation only (Other academic)
National Category
Other Social Sciences not elsewhere specified
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-8759 (URN)
Conference
Veterinärkongressen 2009
Available from: 2009-12-12 Created: 2009-12-12 Last updated: 2017-10-18Bibliographically approved
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